Design for forces induced by seismic torsion

2003 ◽  
Vol 30 (2) ◽  
pp. 328-337 ◽  
Author(s):  
JagMohan Humar ◽  
Soheil Yavari ◽  
Murat Saatcioglu
Keyword(s):  
Static Load ◽  
Building Code ◽  
Torsional Motion ◽  
Analysis Method ◽  
Torsional Response ◽  
Equivalent Static Load ◽  
Torsionally Flexible ◽  
Strength And Stiffness ◽  
Inertia Forces ◽  
Method Of Design

Eccentricities between the centres of rigidity and centres of mass in a building cause torsional motion during an earthquake. Seismic torsion leads to increased displacement at the extremes of the building and may cause distress in the lateral load-resisting elements located at the edges, particularly in buildings that are torsionally flexible. For an equivalent static load method of design against torsion, the 1995 National Building Code of Canada specifies values of the eccentricity of points through which the inertia forces of an earthquake should be applied. In general, the code requirements are quite conservative. They do not place any restriction on the torsional flexibility, however. New proposals for 2005 edition of the code which simplify the design eccentricity expressions and remove some of the unnecessary conservatism are described. The new proposals will require that a dynamic analysis method of design be used when the torsional flexibility of the building is large. Results of analytical studies, which show that the new proposals would lead to satisfactory design, are presented.Key words: torsional response to earthquake, natural torsion, accidental torsion, design for torsion, National Building Code of Canada, interdependence of strength and stiffness.

Torsional motion of buildings during earthquakes. II. Inelastic response

1998 ◽  
Vol 25 (5) ◽  
pp. 917-934 ◽  
Author(s):  
J L Humar ◽  
P Kumar
Keyword(s):  
Building Code ◽  
Elastic Response ◽  
Earthquake Response ◽  
Torsional Motion ◽  
Inelastic Response ◽  
Torsional Response ◽  
Earthquake Motion ◽  
Building Models ◽  
Edge Based

In a previous study on the elastic torsional response of building models subjected to earthquake motion, it was shown that the current provisions of the National Building Code of Canada for design against torsion induced by earthquakes are quite conservative for the flexible edge of the building, but may be inadequate for the stiff edge. Based on the results of studies on the elastic response, a new set of design provisions was suggested. The present study deals with the inelastic torsional response of single- and multi-storey buildings designed according to the suggested provisions. Effects of both the natural and the accidental torsion are considered. It is shown that, given the complexity of inelastic response, particularly that of multistorey buildings, the suggested provisions can reasonably be used for the torsion design of single-storey buildings, as well as of multistorey buildings that are asymmetric in plan, but otherwise fairly regular.Key words: earthquake response, natural torsion, accidental torsion, inelastic torsional response, design for torsion.

Determination of seismic design forces by equivalent static load method

2003 ◽  
Vol 30 (2) ◽  
pp. 287-307 ◽  
Author(s):  
JagMohan Humar ◽  
Mohamed A Mahgoub
Keyword(s):  
Seismic Design ◽  
Static Load ◽  
Base Shear ◽  
Uniform Hazard Spectra ◽  
Uniform Hazard Spectrum ◽  
Higher Mode Effects ◽  
Mode Effects ◽  
Equivalent Static Load ◽  
Adjustment Factors ◽  
Mode Vibration

In the proposed 2005 edition of the National Building Code of Canada (NBCC), the seismic hazard will be represented by uniform hazard spectra corresponding to a 2% probability of being exceeded in 50 years. The seismic design base shear for use in an equivalent static load method of design will be obtained from the uniform hazard spectrum for the site corresponding to the first mode period of the building. Because this procedure ignores the effect of higher modes, the base shear so derived must be suitably adjusted. A procedure for deriving the base shear adjustment factors for different types of structural systems is described and the adjustment factor values proposed for the 2005 NBCC are presented. The adjusted base shear will be distributed across the height of the building in accordance with the provisions in the current version of the code. Since the code-specified distribution is primarily based on the first mode vibration shape, it leads to an overestimation of the overturning moments, which should therefore be suitably adjusted. Adjustment factors that must be applied to the overturning moments at the base and across the height are derived for different structural shapes, and the empirical values for use in the 2005 NBCC are presented.Key words: uniform hazard spectrum, seismic design base shear, equivalent static load procedure, higher mode effects, base shear adjustment factors, distribution of base shear, overturning moment adjustment factors.

scholarly journals Numerical Simulation of Dynamic Response and Evaluation of Flexural Damage of RC Columns under Horizontal Impact Load

2021 ◽  
Vol 11 (23) ◽  
pp. 11223
Author(s):  
Bin Hu ◽  
Jian Cai ◽  
Jiabin Ye
Keyword(s):  
Static Load ◽  
Impact Load ◽  
Bending Moment ◽  
Internal Force ◽  
Displacement Curve ◽  
Fe Model ◽  
Damage State ◽  
Rc Columns ◽  
Equivalent Static Load ◽  
The Impact

By using the ABAQUS finite element (FE) model, which has been verified by experiments, the deformation and internal force changes of RC columns during the impact process are investigated, and a parametric analysis is conducted under different impact kinetic energies Ek. According to the development path of the bottom bending moment-column top displacement curve under impact, the member is in a slight damage state when the curve rebounds before reaching the peak and in a moderate or severe damage state when the curve exceeds the peak, in which case the specific damage state of the member needs to be determined by examining whether there is a secondary descending stage in the curve. Accordingly, a qualitative method for evaluating the bending failure of RC column members under impact is obtained. In addition, the damage state of RC columns under impact can also be quantitatively evaluated by the ratio of the equivalent static load Feq and the ultimate static load-bearing capacity Fsu.

scholarly journals Calculation of Pile Side Friction by Multiparameter Statistical Analysis

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Zhijun Zhou ◽  
Yaqin Dong ◽  
Peijun Jiang ◽  
Dandan Han ◽  
Tong Liu
Keyword(s):  
Statistical Analysis ◽  
Static Load ◽  
Load Test ◽  
Load Testing ◽  
Analysis Method ◽  
Static Load Test ◽  
Statistical Analysis Method ◽  
Loess Region ◽  
Side Friction ◽  
Static Load Testing

In this paper, a static load test and a multiparameter statistical analysis method are used to study the value of pile side friction in different soil layers in a loess region. Currently, static load testing is the most commonly used method to determine the bearing capacity of pile foundation. During the test, a vertical load is applied at the top of the pile, the data under each load level are recorded, and a Q-S curve is drawn to obtain the ultimate bearing capacity of a single pile. Reinforcement stress gauges are installed at different sections of the pile body, and then the axial force and the pile side friction of each section are calculated. Few studies have investigated the calculation of pile side friction in different soil layers using the multiparameter statistical analysis method. Obtaining accurate results using this method will provide an important supplement to the calculation of pile side friction and will also be conducive to the development of theoretical calculation of pile side friction. Therefore, taking Wuding Expressway project in loess region as an example, the lateral friction resistance of six test piles is studied through static load testing and multiparameter statistical analysis. The multiparameter statistical analysis method is compared with the static load test results, and the error is controlled within 20%. The results show that the calculation results of multiparameter statistical analysis essentially fulfill engineering requirements.

Equivalent Static Wind Loads on Low Rise Buildings

2013 ◽  
Vol 671-674 ◽  
pp. 450-453
Author(s):  
Fang Hui Li ◽  
Ming Gu ◽  
Shi Zhao Shen
Keyword(s):  
Static Load ◽  
Wind Loads ◽  
Load Response ◽  
Equivalent Static Load ◽  
Equivalent Static Wind Loads ◽  
Correlation Techniques ◽  
The Many ◽  
Proper Orthogonal ◽  
Fluctuating Wind ◽  
Weighted Combination

The many low rise roof structures are sensitive to the effects of fluctuating wind load. In engineering design for the structures, spatiotemporally varying wind loads on the low rise roofs are modeled as equivalent static wind loads. In this paper, the equivalent static load of the large span roofs is formulated in terms of either a weighted combination of modal inertial load components, and the resonant and background load components that was obtained by the POD (Proper Orthogonal Decomposition) and LRC (Load –Response -Correlation) techniques.

scholarly journals Analysis of Intensity and Vibration of 190T Electric Wheel Dump Truck Frame

2011 ◽  
Vol 2-3 ◽  
pp. 1008-1013
Author(s):  
Xiao Guang Yu ◽  
L. Yang
Keyword(s):  
Frame Structure ◽  
Weak Links ◽  
Dump Truck ◽  
Strength Analysis ◽  
Analysis Method ◽  
Element Analysis ◽  
Stiffness Analysis ◽  
The Finite Element Analysis ◽  
Strength And Stiffness ◽  
Analysis Of Performance

Through the cracking failure analysis of dump truck frame with large electric wheel, the static and dynamic frame analysis of performance evaluation are conducted by the finite element analysis method. From the strength and stiffness analysis frame structure in the weak links, it is easy to find out crack the parts and the reasons with frame, and through the modal analysis and random vibration and fatigue strength analysis the danger frequency of the frame induced by road encourage is obtained, which can prevent the occurrence of frame cracks and provide a foundation for further optimization of the frame.

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